The present invention relates generally to welding-type systems and, more particularly, to a welding torch operable with such systems.
Welding-type systems generally include a power source constructed to generate a welding-type power. The welding-type power is communicated to a torch assembly or a welding gun via a weld cable that extends between the torch and the power source. Some systems include a consumable weld wire that is fed to the torch. The consumable weld wire can be pushed or pulled using a single motor wire feeder, or can be push/pulled by a dual motor wire feeder having a first motor near the power source and a second motor nearer to, or supported by the torch. During a welding process, actuation of a trigger of the torch actuates the motor(s) thereby delivering the consumable weld wire from the torch to a weld.
Torches that include a wire feed assembly, commonly referred to as a wire feeder, allow for operation of the torch at greater distances from a power source and/or use of consumable weld wires that are incapable of being only pushed to the torch. That is, if the distance between the wire feed assembly and the torch is too great, the wire feed assembly will not be able to overcome the friction or drag associated with pushing the weld wire to the torch. Additionally, some consumable weld wires cannot support the stresses associated with being pushed and/or pulled from the power source to the torch and must therefore be located at the torch and delivered to a weld therefrom. Positioning the wire feed assembly on the torch also allows for efficient control and operation of the wire feed assembly. An operator is not required to return to the power source to adjust the wire feed assembly.
During a welding process, the consumable weld wire passes between a pair of the rolls of the wire feed assembly. The wire feed assembly includes a motor that operatively engages at least one roll of a pair of rolls. Operation of the motor rotates the roll and thereby moves the consumable weld wire through the torch and to a weld. The rolls are often separable to allow the initial positioning of the consumable weld wire therebetween. This process is often referred to as “threading” of the wire feed assembly and requires that the rolls be located in a threading position. When located in the threading position, the rolls are moved apart to form a gap between the rolls. This gap is generally large enough to allow the consumable weld wire to move freely between the rolls. Once the consumable weld wire is positioned between the pair of rolls, the rolls are positioned snuggly against the wire, or in a feed position, such that rotation of the rolls “feeds” the weld wire through the wire feed assembly. This threading of the wire feed assembly must be repeated every time a terminal end of the consumable weld wire exits the rolls or an operator desires an alternative consumable weld wire.
A cam is often employed to separate the rolls so that the consumable weld wire can be thread therepast. The cam can engage one roll or both rolls and, when actuated, forms the separation between the rolls necessary to pass the consumable weld wire freely therebetween. These cams require constant operator actuation to maintain the separated condition of the rolls. This requires an operator to maintain hand contact with the cam at all times during the threading process. Additionally, once a threading process has begun, if the consumable weld wire, the spool the consumable weld wire is mounted upon, the weld cable, the power source, or any other component of a welding system requires adjustment, the operator only has one hand available to make such adjustments while maintaining the rolls in the separated position. Occasionally, during a threading process, the consumable weld wire may become stuck in the weld cable which communicates the consumable weld wire to a torch. Freeing of the consumable weld wire often requires manipulation of the weld cable to allow the continued passage of the weld wire therethrough. If the operator requires two hands to manipulate the weld cable to free the consumable weld wire, the threading process must be suspended until the manipulation of the weld cable is complete. That is, the cam must be released and later re-engaged to continue the threading process every time a two-handed adjustment of the welding system is required during a threading process. Accordingly, such wire feed assemblies often require an operator to repeatedly open and close the rolls of the wire feed assembly during a threading process. As such, manually passing the consumable weld wire through the wire feed assembly can be a time consuming and frustrating process.
Once the consumable weld wire has been threaded to the torch, the weld wire can be delivered automatically therefrom by the wire feed assembly. Occasionally, responsive to arc/weld performance, an operator needs to adjust the rate of delivery, or feed speed, of the consumable weld wire. The wire feed assembly often includes a control connected to the motor of the wire feed assembly to facilitate adjustment of the wire feed speed. Welding systems that have a wire feed assembly supported on the welding torch also often have a feed control supported thereon. Positioning the feed control on the torch eliminates an operator's repeated trips away from a workpiece and/or torch assembly to adjust the wire feed speed. The feed control often includes a knob or dial that is accessible through a housing or handle of the torch. The knob is connected to a shaft of the control such that rotation of the knob adjusts the signal output from the control. Although mounting the wire feed control in the torch is convenient and efficient for operator manipulation of the control, it is not without its drawbacks.
A control that is supported by the torch is also subject to the movements and impacts subjected to the torch. That is, during a welding process, the torch can be repeatedly subjected to impacts. For example, during welding processes, slag can collect in a nozzle of the torch. Rather than removing the nozzle from the torch to remove the slag therefrom, some operators tap the torch on a work surface to remove the slag from the nozzle. Occasionally, attempting to ensure that the torch and weld cable are clear of a work area, an operator will manipulate a position of the torch by manipulation of the weld cable. Understandably, the torch, and any components supported thereon, must be ruggedly constructed to withstand these and other rigors associated with a workplace and weld processes. Not only do the impacts to the torch affect the operation of the wire feeder attached to the torch, they can also affect the setting of the feed control connected thereto.
Each impact that the torch is subjected to also imparts a portion of these forces on the components of the feed control. Occasionally, these forces result in inadvertent adjustment of the feed control. In addition to the impact forces the torch is subjected to, the torch is also repeatedly gripped and released during a welding process. This repeated gripping and releasing of the torch can also result in inadvertent adjustment of the feed control. That is, the feed control may inadvertently and unknowingly experience an adjusting contact with an operator's clothes or gloves, a workpiece, or other workplace obstructions such as a workpiece. Accordingly, if an operator does not confirm the setting of the feed control with each successive gripping of the torch, actuation of the trigger of the torch would result in operation of the wire feed assembly at an undesired feed speed. Attempting to weld at a feed speed that is unknown and/or undesired will result in poor, if any, weld arc performance.
Maintaining the wire feed speed at a desired value for the duration of a welding process allows for efficient and extended operation of the welding torch. Accordingly, a single operator of the welding torch can achieve greater efficiency with decreased delay between successive weld processes. Such efficiency achieves extended periods of welding system operation by an individual operator. As such, operator fatigue must also be considered in constructing such torches. The weight, ergonomic impact, and operating temperature of the torch are only three of many considerations that must be addressed in constructing a torch that can be operated for extended periods by a single operator. Torches are often operated by a single hand of an operator thereby allowing for workpiece manipulation by the operator's free hand. The torch must be constructed to comfortably fit in a grip of an operator. This requirement often requires miniaturization of internal components of the torch and a handle assembly that can support the heat and power requirements associated with extended operating periods. Often times, the conductors that communicate the welding power through the torch include several individual conductors that extend along the length of the torch handle. Multiple conductors allows the torch to accommodate other components, such as a trigger assembly and/or a wire feed assembly, while maintaining a single hand graspable torch. Additionally, partitioning the weld power across several conductors reduces the amount of heat generated by each individual conductor as compared to a torch required to communicate the same weld power through the torch over fewer conductors. However, diversifying the weld power across the several conductors does not decrease the total amount of heat generated in the torch assembly by the communication of the weld power therethrough.
In addition to the weld power, a weld gas is also communicated through the torch assembly to a weld. The weld gas is often directed through one of the weld power conductors rather than providing a dedicated conduit for the weld gas. Passing the weld gas through a single conductor provides an adequate flow of weld gas to a weld process and provides some degree of cooling of the torch assembly. However, temperature of the torch assembly is an issue when the torch is operated for extended durations and at increased weld powers. That is, the passage of weld gas through a single conductor of the torch assembly limits the amount of weld power and the duration of weld intervals that a torch can provide. Other torches utilize a water cooling loop that circulates a fluid cooling flow the conductors of the torch. Such torches can operate at higher weld powers as compared to torches having weld gas cooling systems but are difficult to maintain and more expensive to manufacture and operate. Such torches must be fluidly connected to a reservoir and pump to circulate the cooling fluid therethrough. Additionally, such torches require that at least two of the conductors be fluidly connected within the torch to form a circulation loop for the cooling flow. Accordingly, these torches require complex assembly and precision manufacture to ensure that the fluid loop is isolated from the other components of the torch.
In addition to the heat generated by the communication of the weld power through the handle of the torch, the portion of the torch that extends beyond the handle portion, or the barrel assembly, is also susceptible to thermal accumulation. A nozzle is positioned at a distal end of the torch assembly and is positioned in very close proximity to a weld during a welding process. The barrel assembly is generally disposed between the nozzle and the handle portion of the torch. As the consumable weld wire is discharged from the handle portion of the torch, the barrel assembly directs the consumable weld wire and the weld gas delivered from the torch assembly to a weld. The close proximity of the barrel assembly to the weld process exposes the barrel assembly to the considerable thermal energy associated with a weld process. That is, the barrel assembly experiences convection and radiation heating due to its proximity to a welding operation.
In addition to the convection and radiation heating of the barrel assembly, a portion of the heat communicated to the barrel assembly is conducted through internal components of the barrel assembly. A plurality of tubes is internal to the barrel assembly and isolates the communication of the consumable weld wire, weld power, and weld gas to a weld. As the weld wire is consumed during a welding process, heat is conducted along the length of the weld wire into the barrel assembly. Some of this heat is transferred to the plurality of tubes and therefrom to an exterior surface of the barrel assembly. Similarly, the nozzle of the torch assembly is supported by the barrel assembly and located in close proximity to the weld pool during a welding process. As such, heat collected in the nozzle is also conducted to the barrel assembly.
The length of the nozzle and barrel assembly, in addition to the gap between the torch and the workpiece, is often all that determines the distance of an operator's hand from the weld pool. That is, a trigger of the torch is often mounted on the torch assembly in relatively close proximity to the barrel assembly. As such, an operator is often exposed to the heat that is accumulated in the barrel assembly of the torch. Even located in a heavy glove, an operator's hand can still perceive and be subjected to the heat of the barrel assembly of the torch. Occasionally, after extended periods of torch operation, the accumulation of heat in the barrel assembly can result in an operator's inability or unwillingness to operate the torch, or if unaddressed, result in damage to the barrel or the torch assemblies.
It would therefore be desirable to provide a torch assembly that has a wire feed assembly having a pair of rolls securable in a position necessary to pass a consumable weld wire freely between. It would further be desirable to provide a feed control for the wire feed assembly that is resistant to inadvertent adjustment of the control. It also would be desirable to have a torch assembly having a plurality of weld gas passages formed therethrough. Additionally, it would also be desirable to provide a barrel assembly that thermally separates an outer surface of the barrel assembly from the internal components thereof.